Early Heraldic literature was not confined to England. John of Guildford referred to Bartholus as a great authority on the subject of Heraldry. This Bartholus or Bartolo of Sassoferrato was a well know medieval Italian jurist who died in 1356. He has been referred to as the father of international law. He lived from 1314 to 1356 and was at different times professor of law at Bologna, Pisa and Perugia universities. His book Tractatus de Insigniis et Armis, is the earliest known composition on Heraldry.
The English writers of these early times follow him closely, quoting him as decisive on disputed points of law. His treatise can be seen in the British Museum in a copy dated to 1475 in black letter Latin. In the relevant portion of the book Bartholus says, after dealing with the arms proper to princes: “ There are certain insignia or arms of private men or nobles or of peoples, among these are some who bear arms and insigniawhich have been granted to them by the Emperor or some other lord, as I have seen granted to many by the most serene prince Charles the 4th, Holy Roman Emperor and King of Bohemia. To me also, his councilor, he granted arms among the rest, so that I and others of my family should bear a red lion,, double tailed, on a field of gold ( Or a lion gules double queued). That such persons are able to bear arms there can be no doubt, for it is sacrilege to dispute the power of a prince. In addition, some take arms to themselves of their own authority and it should be considered whether this is lawful. And I think this is lawful, just as names were invented to distinguish men. In this way insignia were invented for the same purpose, and just as one is allowed to take names at pleasure, so too one may take arms and place them on his own shield but not on anothers. “
Bartholus gives careful consideration to the position of persons who, not being of the same blood, yet have the same arms. “ For instance a German went to Rome in the time of indulgence where he found a certain Italian who bore the arms of his ancestors. He wished to complain of this. But indeed he could not, for so great is the distance between both places , that the former man could not be injured by this. “ Bartholus agrees that a skillful smith who puts a mark on his sword and whose workmanship makes his weapons sought after, should be able to protect his own trademark; so too should notaries and mapmakers.” What then”, he asks “ is the value of a grant of arms from a prince? First, that is of greater dignity. Second, that no one can prohibit one from wearing them. Third, because if two persons assume the same arms, and there appears no difference in priority, he is preferred who had his arms from the prince. Fourth, if one is in the army or in any other place, and questions arise as to precedence, those arms should be preferred which are granted by a prince.”